Orifice shoe for well pipes



Oct. 23, 1951 C. C. BROWN r ORIFICE SHOE FOR WELL PIPES Filed Aug. 9,1948 C. C. Brown INVENTOR.

A r roma-y Patented Oct. 23, 1951 UNITED STATES PATENT OFFlCE ORIFICESHOE FOR WELL PIPES Cicero C. Brown, Houston, Tex.

Application August 9, 1948, Serial No. 43,296

6 Clams.

This invention relates to shoes for well pipes and particularly to shoesfor use on pipes which are to be cemented in a well bore.

In conventional methods of cementing pipe strings in a well, the pipe tobe cemented is normally provided at its lower end with a device,commonly termed a "float shoe" in the cementing, art. A conventionalfloat shoe generally comprises a hollow body rounded at its lower end toform a guide for the lower end of the pipe and having one or more fluidpassageways through the wall thereof for the discharge of cement orother fluid from the bore of the pipe into the annular space between thepipe and the well bore. A back-pressure check valve of conventionaldesign -is ordinarily installed in the bore of the shoe to preventreturn flow of cement or other fluid from the annular space into theinterior of the pipe.

Well bores in which a pipe is to be cemented will normally be filledwith drilling mud or other fluid and when a pipe string fltted with aconventional shoe is inserted in the well bore, the check valve willprevent entrance of such fluid into the interior of the pipe string andwill render the pipe buoyant in the fluid, hence the term "float shoe.The pipe string must, therefore, be loaded with other fluid to overcomethis buoyancy to permit the pipe string to sink into the well bore andto balance the external fluid pressure to prevent Collapse of the pipe.This operation necessarily involves delay and added operations toeffectively snk the pipe string into the well bore. Also, the loadingfluid may often be of different character than the fluid initiallypresent in the well and when displaced into the well bore during thecourse of the cementing Operations, may have deleterious eflects uponthe wall of the well bore, particularly in open hole cementing, whichmay adversely affect the character of the bond subsequently formedbetween the cement and the wall of the well bore. Still another seriousobjection to the use of conventional float shoes arises from the pistonefect produced on the fluids in the well bore when a pipe, having itslower end closed by such a shoe, is lowered in the well. The closeclearances ordinarily provided between the inserted pipe and the wellbore, or intermediate pipe string, and the usually viscous nature of themud fluids in the well are generally responsible for producing thiseffect which, particularly in the case of long strings of pipe, may'result in the exertion of great pressures on the fluid trapped below theconventional float shoe. s Un- (CI. ISS- 1) 2 der the pressures thusdeveloped, the viscous mud fluids may be forced so deeply into the poresand crevices of the surrounding formations, particularly those fromwhich oil or gas production is sought, as to entirely or partially plugthese formations to an extent such that when the pressure is eventuallyrelieved, the oil or gas cannot escape into the well and may result infailure of the well to produce successfully.` y

The present invention has for its principal object the provision of ashoe for well pipes having a novel form of flexible crifice thereinthrough which fluid present in the well bore is admitted at a regulatedrate into the pipe string to fill the stringas the pipe is lowered intothe well.

An important object is the provision of a pipe shoe having a flexibleorifice which will automatically close in response to excessivevelocities of fluid flow therethrough.

Other and more specific objects and advantages of this invention willbecome apparent from the following detailed description when read inconjunction with the accompanying drawings which illustrate a usefulembodiment in accordance with this invention.

In the drawings:

Fig. 1 is a longitudinal sectional View of the shoe, showing itconnected to the end of a pipe inserted in a well; and

Fig. 2 is an exploded View showing the parts of the shoe inquarter-sectional elevation.

Referring to the drawings, the shoe in accordance with this inventioncomprises a tubular body o having an internally threaded box ll at oneend for connection to a pipe l2. An externally threaded ring !3 havingan axial passageway !4 therethrough is adapted to be screwed into thebottom of box H and to seat against an annular shoulder l5 therein. Ring!3 has a cylindrical extension !6 extending into the bore l'! of bodyI!) below the bottom of box i a fiuid-tight and mechanically strongconnecand tapering downwardly to an orifice 24 which. extends axiallythrough the apex of nozzle 20 Nozzle 20 has an l and providescommunication between: bore* 723 i and the interier of bore I'I belowlip 22. Nozzle 20 is thus provided with flexible walls 25 which taperinwardly and downwardly insrbore -l'|.`

The lower end of body I& is threaded at 25 for the attachment of ahousing or cage 21 which is closed at its lower end .and is adapted toencloser'nozzle '2 A=`plu`rality i of' fluid passage'- ways, 281 extendthrough the walls of cage 21 'to providecommunication between the?exterior and interier 'thereof be -provided-with a plurality ofdownwardly directed radial flanges 29 which may be sharpened, asat'3-',to formxcutting or millingiteeth forsthelower *end of the cage.

The lower end` of Cage'Z'may Theeabove described device: is empl'oyed inthe l following manner: :Che shoe is assembled and connectedr'toithellowerend oipipe !2, as illustrated-inFig. 1. Thepipe string is theninserted into-a wellbore 3! which willordinarily be filled with .mudfluid. Asthe pipe enters the fluid, the

latteri'flows through 'passageways 28 nd ent r -C.

the' interior ofcage`2'i. The entering fluid will exert pressure againstlip 22 due to the resistance' set up by the restricted area of orifice24, and will expand lip `22'tightly against the wall of bore I 1, threbyconstraining the fluid to flow through orifice 24 in order 'tol'enterthe interior of the pipe 'string." Th rate'at which the fluid willflowbackthrough orice 24 'willnecessarily be determined by its area andthe back pressure of th'e fiuid; The restriction formed by orifice 24will necessarily develop back pressure on the fluid which will begoverned largely by the Velocity at which the pipe string is loweredthrough the fluid; This back pressure will,` of course, be exerted'against the exterior of walls 25 of the ori- Since walls 25 are'fiexible and infice nozzle. wardly tapered, 'as llustrated, when thefluid pressure'thusexerted against the exterior of the Walls exceedssome critical pressure, depending upon the fiexn strength of walls 25,the walls will be caused tocollapse inwardly and will thereby'effectively shut-off bore 23. will'be evident that; if pipe l2 islowered into Accordingly', it

the' well at an eXcessiVe velocity, the nozzlewalls' willpromptly`collapse, shutting off the entrance oftfluid into the pipe andimmediately stop further descent oi the pipe. If the rate of descent of:the pipe is then reduced sufiiciently, the natural'resilience of'walls25 Will cause them to expand and again admit fluid to the interier ofthe pipepand permit further descent of the pipe into' the l Well.

Itiwill be seen, therefore, that by means of this novel 'form of orificenozzle, a, pipe string may be lowered .into` a well bore full of fluidat a regulated rate' which permits the pipe to fill up with the' fluidin the well at a controlled rate and which will eliminate the necessityfor the loading Operations, heretofore required and which will, atthezsame time, eliminate the pisten efiect on the surrounding earthformations produced by the use of conventional float shoes. At the sametime, the pipe string may be lowered into the well at any desired speed,depending largely upon the area of orifice 24, and the collapsingstrength of walls 25. The area of orifice 24 will be determinedgenerally in some suitable relation to the area of the pipe string whichis calculated to allow the pipe to sink at a desired speed below whichthe resulting velocity pressure exerted against walls 25 of the nozzlewill be less than the collapsing strength of nozzle.

When a pipe equipped with the above-described 'orifice 'shoe has beenlowered, as described, to the desired depth in a well, cement or'otherfluid' may be forced through the interior of the pipe andpa'ss throughnozzle 20 and thence through passageways 28 into the annular spacebetween the pipe and the well bore in the conventional manner. Incementing Operations, the Shoe-in accordance* with this invention may beused with cementing plugs, such as those 'described in my co -pendingapplications, Serial Nos. 43297 and 46,221, filed August 9, 1948 andAugust 26,'1948, respectively, which are designed to serve s asee'ctiveback-pressure valves to prevent ref-: turn flow`=of cement or otherfluidfrom the' an- Alter-J- natively,'--the orifice shoe herein describedmay' nular space to the' interier of' the pipe.

itself serve 'as back-pressure valvej When a body of cement has beendisplaced' into 'the annular spaeesinthe' conventional' manner, thehydro-' static pr'essure of 'the resulting column of cement; becauseitsspecic gravity'is normally greater thanthe displacing fluid inside thepipe,'wil1 over-balance that of -the 'column of displacing fluid: insidethe pipe and attempt to flow back in-' According to'the pipethrough 'theorifice Shoe. ly, if the pressure on the displacing fluid inside the`pipe' is 'suddenly relieved, as by' pulling 'a va'cuum'on 'the pipe, theresulting sudden backward rush'of cement will develop a velocitypressure exceeding the collapsing strength of nozzle 23 and cause thelatter to'shut-ofi, thereby effectivelyblocking the return flow of thecement, and the nozzle Will remain shut-ofi as long as this'excess`pressure is'maintained 'or until the cement has hardened.

It 'will be understood that various changes and alterations may be` madein the details of the illustrativ'e embodiment herein described withoutdeparting from the scope of'the appended claims but within the spirit ofthis invention.

What I claim and desire to secure by Letters Patent is:

1.'A shoe for well pipes, comprising, a generally tubular body adaptedto be connected at one end to a well pipe, a generally conical hollownozzle member constructed of flexible resilient materialaxially disposedin said body with its apex directed toward the opposite end thereof andhaving the periphery of its base portion in sealing enga gement with thewall of said body, andan axial orifice of restricted area through -theapex of said nozzle member.

2. A Shoe for Well pipes, comprisin'g, a generally tubul'ar body adaptedto be connected at one end to a 'well pipe, a generally conical hollownozzle member constructed of flexible resilient materia1`axially`disposed in' said body with its apex dire'cted toward the opposite endthereof and having the periphery of its base portion in sealing'engag'ement' with the wall of said body, an axial orifice of'restrictedarea through the apex-:of said nozzle member, and a perfora'te housingconnected to said opposite end of said body and enclosing said nozzlemember.

3. A shoe for well pipes, comprising, a generally tubular body adaptedto be connected at one end to a well pipe, a generally conicai hollownozzle member constructed of flexible resilient material axiallydisposed in said body with its apex directed toward the opposite endthereof, a fiexibe peripheral lip about the base portion of said nozzlemember expandible into scaling engagement with the wall of said body,and an axial orice of restricted area through the apex of said nozzlemember.

4. A shoe for well pipes, comprising, a generally tubular body, aninternally threaded box in one end of said body for connecting said bodyto a pipe, an externally threaded ring inserted in said box, a generallyconical hollow nozzle member disposed in said body having its baseportion connected to said ring and in sealing engagement with the wallof said body and having its apex extending toward the opposite end ofsaid body, the walls of said nozzle member being constructed of flexibleresilient material, and an axial orice of restricted area through theapex of said nozzle member.

5. A shoe for well pipes, comprising, a generally tubular body, anintemally threaded box in one end of said body for connecting said bodyto a pipe, an extemally threaded ring inserted in said box, a generallyconical hollow nozzle member disposed in said body having its baseportion connected to said ring and having its apex extending toward theopposite end of said body, a

flexible peripheral lip about said base portion expandible into sealingengagement with the wall of said body, the walls of' said nozzle memberbeing constructed of 'flexible resilient material, and an axial orice ofrestricted area through the apex of said nozzle member.

6. A shoe for well pipes, comprising, a generally tubular body, aninternally threaded box in one end of said body for connecting said bodyto a pipe, an externally threaded ring insertible in said box, agenerally conical hollow nozzle member having its base portion connectedto said ring and having its apex extending toward the opposite end ofsaid body, a flexible peripheral lip about said base portion expandibleinto sealing engagement with the wall of said body, the walls of saidnozzle member being constructed of flexible resilient material, an axialorice of restricted area through the apex of said nozzle member, and aperforate housing connected to said opposite end of said body andenclosing said nozzle member.

CICERO C. BROWN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 996,588 Kennedy June 27, 19111,810,420 Getty June 16, 1931 2,308,955 Wilson et al Jan. 19, 1943

